Add identifier for CID extension
Add identifier for CID extension

Note: The current draft

   https://tools.ietf.org/html/draft-ietf-tls-dtls-connection-id-04

does not yet specify the extension value, so we
use a temporary value of 42.

Mbed-TLS/mbedtls,NXPmicro/mbedtls,Mbed-TLS/mbedtls,ARMmbed/mbedtls,NXPmicro/mbedtls,ARMmbed/mbedtls,NXPmicro/mbedtls,NXPmicro/mbedtls,ARMmbed/mbedtls,ARMmbed/mbedtls,Mbed-TLS/mbedtls,Mbed-TLS/mbedtls